Feeding habits of the sesarmid crab Perisesarma bidens (De Haan) in the mangroves of the Ryukyu Islands, Japan

Feeding habits of the sesarmid crab Perisesarma bidens (De Haan) was investigated in the mangroves of the Ryukyu Islands, Japan. Stomach content analysis showed that their diet consists mainly of mangrove leaves fragments, with small amounts of animal, algae and sediment matters, indicating that P. bidens is primarily detritivorous. The consumption rate of P. bidens was investigated under laboratory conditions by offering three different types of Kandelia candel mangrove leaves. Crab survived by eating green, yellow or brown leaves, preferring brown to either green or yellow leaves. Consumption rate of brown leaves was significantly higher when crabs were provided with green, yellow and brown leaves together, than when provided separately. It is considered that the brown leaves have a soft tissue, which is easily torn by the crab chelae and have apparently low C/N ratio. The C/N ratio of faeces, which indicated lower value than that of burrow leaves or sediments, derived from the symbiosis of bacteria in the stomach. The C/N ratio showed that sediments had C/N ratios 2/3 times lower than leaves sequestered in the burrow, indicating that mangrove sediments could have higher nutritional value than mangrove leaves. Perisesarma bidens showed significant consumption rates of mangrove detritus, therefore, it may have the important role as the grazer of mangrove detritus in view of the nutrient cycle in the mangroves.

Ecological models and GIS maps of macroalgae, as bioindicator for ecological status of Hormozgan rocky shores

In this study a total of 75 species were identified, from which 17 species, 9 genes and 6 families; belonged to Green Algae, 18 species, 7 genes and 4 families; belonged to Brown Algae, and 40 species, 18 genes and 11 families; belonged to Red Algae. From total times spent for sampling, it was determined that at lengeh harbor with 6 species, had the lowest diversity of green algae. The species diversity of brown algae at Michael location with 10 species each; had the highest, and Tahooneh location with 5 species; had the lowest species diversity. Species diversity of red algae at Michael location with 28 species; had the highest, and Sayeh Khosh location with 13 species; had the lowest diversity. From all locations where sampling took place, the highest species diversity regarding Time and Space for all three groups of algae; were associated to Late February (20th. Feb. ), and late March(20th. March). Coverage data of macroalgae and Ecological Evaluation Index indicate a high level of eutrophication for the Saieh khosh, and Bostaneh, They are classified as zones with a bad and poor ecological status. It has been proved that concentrations of biogenic elements and phytoplankton blooming are higher in these zones. The best values of the estimated metrics at Tahooneh and Michaeil could be explained with the good ecological conditions in that zone and the absence of pollution sources close to that transect . The values of abundance of macroalgae and Ecological Evaluation Index indicate a moderate ecological conditions for the Koohin, Lengeh and Chirooieh.

Status of the biodiversity of St. Martin's Island, Bay of Bengal, Bangladesh

A total of 234 species of fish have been recorded from the St Martin Island. Of which, 98 species are coral associated. The total number of recorded mollusc and crab species stands at 187 and 7 species respectively. A total of 66 coral species were recorded, of which 19 are fossil corals, 36 living corals and the rest are under 6 families of subclass Octocorallia (soft corals). A total of 14 species of algae have been recorded from the St. Martin's Island. There is an estimated amount of 1500 MT red sea weed biomass available around the St. Martin's Island. The island contains some of the most unique, benthic community associations in Bangladesh, not found anywhere else in the South Asian region. The unique marine communities have very high scientific value for research and monitoring and there are only a few examples worldwide, where coral-algal communities dominate rocky reefs. The economy of the island is based on fishing. It is estimated that, about 1650 MT of fish are caught annually. Over-exploitation of renewable marine and coastal resources (e.g., rocky reef fisheries, coral and shell extraction; removal of coastal vegetation from inter-tidal and sub-tidal habitats) is a major threat to this ecosystem. Destructive fishing practices, mainly the use of rock-weighted gill nets over the inshore boulder reefs is of prime aggravates. Proper implementation of the rules and regulation for Ecologically Critical Areas (ECA's), alternative livelihood for the local people and further research should be immediately taken for sustainable utilization and to save the rich biodiversity of the only coral island in Bangladesh.

Fatty acid composition of some brown seaweeds (Phaeophyta) from the coast of Karachi

Ten species of filamentous and multicellular thalloid algae (Phaeophyta) belonging to six genera of the class Dictyophyceae were collected from different seawater habitats of Karachi, Pakistan at the northern boundary of the Arabian Sea during September 1997 and July 1998. They were extracted in chloroform: methanol, saponified, subjected to column chromatography (CC, TLC), esterified and analysed for fatty acid (FA) composition initially by gas-liquid-chromatography (GLC) and finally by gas chromatography-mass spectrometry (GC-MS). Algae of the classes Laminariophyceae and Fucophyceae (Phaeophyta) displayed only a few SCFAs, PUFAs and substituted FAs, no VLCFA, C22 UFA, CFA, DCFA and monoynoic FA, large amount of C16:0, very large quantity of C18:1, very small RCCL and FA-diversity, C18 UFAs up to four DBs, C20 UFAs up to three DBs only. They were characterized by the largest amount of C18:1, lowest degree of unsaturation of C20 UFAs, lack of C22 UFAs, the shortest RCCL and the smallest FA-diversity as compared to other phyla.

Fatty acid composition of more brown seaweeds (Phaeophyta) from the coast of Karachi

Six species of multicellular, thalloid, brown algae, belonging to five genera of the classes Laminariophyceae and Fucophyceae were collected from the coastal areas of Buleji near Karachi (Pakistan) during October 1997 and February 1998. They were extracted in chloroform: methanol, saponified, subjected to column chromatography (CC, TLC), esterified and analysed for fatty acid (FA) composition initially by gas-liquid-chromatography (GLC) and finally by gas chromatography-mass spectrometry (GC-MS). They displayed only a few SCFAs, PUFAs and substituted FAs, no VLCFA, C22 UFA, CFA, DCFA and monoynoic FA, large amount of CI6:0, very large quantity of C18:1, very small RCCL and FA-diversity, C18 UFAs up to four DBs, C20 UFAs up to three DBs only. They were characterized by the largest amount of C18:1, lowest degree of unsaturation of C20 UFAs, lack of C22 UFAs, the shortest RCCL and the smallest FA-diversity as compared to other phyla.

Mangrove ecosystem of Red Sea coast (Saudi Arabia)

The present paper reviews critically the existing information on mangrove ecosystem of Saudi Arabian Red Sea coast and identifies problems and shortcomings that should be removed or remedied. Mangrove structure and composition seems to have been substantially studied along with salient environmental features, and these are thoroughly summarized herewith. However, the functional aspects, especially energy flow through the ecosystem, remain totally neglected. Both the flora and fauna indicate severe environmental conditions, such as very low nutrient levels, very high salinity values and hard bottom, which are unique to the area. Mangrove growth and diversity is very poor, although conditions in the southern part are relatively favourable. The extreme poverty of the ecosystem is supported by exports of organic matter from adjacent seaweed and seagrass ecosystems and also Sabakhas. Preponderance of epiphytic and benthic algae within the mangrove ecosystem is another source of nutrient replenishment in the otherwise oligotrophic habitat of Red Sea. Finally, a hypothetical model of energy flow in the ecosystem is proposed.

Chemical ecology fatty acids of mollusks dominant species in intertidal zone of Chabahar Bay

Chemical ecology is the science of study and analysis of natural chemical products in result of biochemical processes in organisms and their reactions to variations of ecological and environmental parameters. In marine chemical ecology the existence of natural products in aquatic organisms and their ecological roles in marine animals and their reactions to environmental parameters variations will be studied. Among them, fatty acids are the most various and abundant ones in natural products which had been extracted from many marine organisms such as mollusks and algae. In this study selected animals were the dominant species of mollusks in intertidal zone of chabahar bay including gastropods, bivalves and polyplacophora classes. Nerita textilis and Turbo coronatus species are among gastropoda, Saccostrea cucullata is from bivalve, and Chiton lamyi is from polyplacophora. After seasonal sampling, separation and identification of natural products of these species, fatty acids had been isolated and identified by GC mass chromatography and their seasonal variations had been identified. In addition environmental factors of the location including pH, salinity temperature, dissolved oxygen, chlorophyll a and nutrients were measured monthly. Then the effect of seasonal variations of environmental factors on fatty acids had been studied by applying statistical analysis. GC/MS resulted thirteen fatty acids, which the most importants were myristic, stearic, oleic, palmitoleic, arachidonic and eicosapentaenoic acids. In majority of species palmitic acid was most abundant than the others and saturatedes had the most percentage levels than unsaturated ones. Although seasonal variations of identified fatty acids was not similar in species, but the majority of unsaturated ones had their maximum during winter, while saturated acids reached their maximum in summer. Statistical Analysis showed the strong correlations between Environmental factors and some fatty acids and temperature, nitrate, silicate and pH had strong correlations in all species. The species was studied from the point of lipid content and the results showed a good quality of lipid content in the selected species in the intertidal zone of Chabahar bay.

The effect of spirulina (fresh and dry) on some biological factors in Penaeus semisulcatus larvae

Spirulina is a filamentous cyanobacteria with many applications in food and drug industries, as a food in human, aquaculture, vet and poultry industries… . Semi and mass culture of Spirulina carries out in different countries. This study was carried out in five phases in order to produce this microalga in Iran. The first phase, Spirulina pure stock was imported from Indonesia. After identification of species, it was cultured in laboratory until we took 20 liters of biomass. The semi-mass culture was carried out in green house. Cell concentration and size of Spirulina were recorded during culture daily and their growth rates were calculated. After two weeks, when the size of Spirulina was suitable, biomass of Spirulina was harvested then accumulated Spirulina weighted and dried in 24 hours in laboratory. In order to microbiological study, the samples of Spirulina (dry and fresh) were cultured on blood agar medium and coliforms were counted. The chemical composition of produced Spirulina was measured by standard methods. Fatty acid and amino acid profiles were acquired by GC and HPLC instruments, respectively. The amount of chlorophyll in Spirulina was determined by spectroscopy method. Also astaxanthin pigment as an important carotenoid was measured by HPLC in Spirulina and Penaeus semisulcatus larvae fed on Spirulina. At final phase of this project, larva fed on produced Spirulina (biomass and dry powder) was compared to Z plus, microencapsulated Spirulina (M.C.F) and Chaetoceros algae as control. This experiment was carried from zoa to early post larvae stage then survival and growth rate of larvae were recorded. The growth rate of larvae was evaluated with ANOVA test and survival rate of treatments was assessed by Log Rank (Mantel –Cox) test. Also during larvae stage, two parameters of water such as nitrate and nitrite were measured in zoa, mysis and post larvae stages. The results of this study were shown that colifom counts were 1.85×106 and 92.3×105 coliform per ml in fresh and dry spirulina, respectively. Protein percent of dry spirulina was 50.93 % (dry weight) and the amount of astaxanthin in spirulina and larvae fed on spirulina were 0.21 and 0.01 mg/kg, respectively. The most survival rate of larvae were observed in zoa III (88.8%) with Z plus supplement treatment, in mysis III (76.5%) combination of Z plus and dry spirulina in comparative between treatments. Larvae growth (4.5mm) of control in early post larvae was the best.

Study of distribution, growth and reproduction polychaetes Nereidae in intertidal zone of Bandar Abbas and effect dominant species on white Indian shrimp brood stocks (Fenneropenaeus indicus)

Distribution of polychaetes worms Nereidae in intertidal zone of Bandar Abbass indicated that distribution rate of worms from the west to east for the reason status of seabed type, habitat and feeding substrate used to worms increased. Also investigation description that last-mentioned worms are belong to Nereididae family, Perinereis genus and species of Perinereis nuntia. By viewpoint seabed soil types experiments implement indicated Nereididae worms have higher survival with sandy clay loam soil texture. Statistical analysis showed positive relation coefficient correlation of Pearson between substrate type to frequency of worms and too substrate type with soil organic matter value (P<0.05). By viewpoint feeding also experiments with different feed treatment indicated that Nereid worms is Omnivore but in natural condition more utilized algae substrate special Entermorpha and survival rate had the worms last-mentioned in dietary treatments on this algae 93/3% different significant with other treatments (P<0.05). In this project pond-reared white Indian shrimp (Fenneropenaeus indicus) were used in four maturation and spawning trials lasting 60 days. one group of shrimps was fed a formulated pelleted special of broodstock diet only, a second group was fed squid meat diet; a third group of shrimps with mollusca (Solen vagina) meat diet and fourth group was fed polychaete worms Nereidae family, collected in intertidal zone of Bandar Abbass. Four types of dietary treatments (M1, M4) were given to separate batches that were run in three duplicate. Results of experiments demonstrate that more grew rate and maturation and spawning rate and we found that shrimps fed with polychaete worms have the best condition and then shrimps fed with solen. This is demonstrate furthermore environmental circumstance, endocrine hormone, types of feed important of maturation and spawning of shrimps and in polychaete worms used HUFA help to maturation ovarian in shrimp.

Assessing potential of production in Lake Choghakhor

Phytoplankton productivity is the common and important factor being considered in determining the overall status of a given body of water. This is because they are found at the base of an energy or food chain, being the basic source of primary food in a given aquatic system. Hence, information on their contribution is essential in indicating how much biomass energy will be available to all other living resources in the system. Though the primary productivity of shallow lakes is characterized by mixed populations of phytoplankton and submersed aquatic vegetation in the open water. Lake Choghakhor, is a shallow lake, located in Chaharmahal-Bakhtiyari Province. This lake is the most important ecosystem in the region especially for waterfowl populations, has a recreational value and supports tourism and fisheries. During last decade Choghakhor has been influenced by some man-made impacts such as water level fluctuation, agricultural discharge and fish (Cyprinids) introduction causing a serious problem in its trophic states. So water quality for physical, chemical and biological was monitored in five sampling stations, from April 2003 to March 2004. As biological parameters we studied phytoplankton, epiphytic algae, and zooplankton and macrobenthose community structure. Chlorophyll a content for phytoplankton and epiphytes was measured to estimate production of these groups (biomass over time). Also we determined biomasses of submersed macrophytes and macrobenthose and primary production of phytoplankton (dark and light bottles technique) to estimate fish production. The results of this study showed Lake Choghakhor did not undergo stable thermal and oxygen stratification, and the lake water was mixed throughout the study (the lake mixing regime is polymictic). Now submerged plants especially Myriophyllum spicatum has covered almost the entire lake and dense macrophyte beds (Polygonom amphibium), located on the east southern end of the lake appear to act as a sink for these nutrients. Lake Choghakhor appeared to be in a macrophyte dominated clear water state with low TP (annual mean: 24± 15μg.l-1) and chlorophyll a (annual mean: 3±1.28μg.l-1) concentrations and very high Secchi depth. The grazing pressure of dominant pelagic filtering zooplankton Daphnia longespina did not seem to be significant in determining the low phytoplankton crop expressed as chlorophyll a. We expect that sequestering of nutrients by submerged plants and associated epiphytes are the dominant stabilizing mechanisms suppressing the phytoplankton crop of Lake Choghakhor.

Effects of toxins induced by phytoplankton bloom on physiological function of indicator animals in Anzali Lagoon

The present overview summarizes data from one year's study during the period of 1379 to 1380 in the regions by "Anzali" lagoon called "Abkenar" and "Hendkhale". Specimens from this lagoon obtained weekly during mordad and shahrivar mounths (July 21 to september 21). The study included 67 types of 5 phytoplanktonal phylum. In "Abkenar" region Cyanobacters with maximum of 97% and minimum of 64.5% of total combination of phytoplanktones made the dominating combination during the period of study , while in "hendkhale" chyrsophyta with maximum of 89% and minimum of 38.7% of total phytoplanktonal was the dominating figure at the same period of time. Researches on ecological parameteres showed that the avarage dissolved oxygen in -Abkenar" and "hendlchale" regions was 10.7 and 8.0 mg/lit respectivly, also total rate of Phosphat in these regions was 0.085 and 0.15 mg/lit respectivly. This study showed that the rates of Nitrat and Amonium in "Abkenar" region was 0.043 and 0.79 mg / lit while for the same substances in "Ilendkhale" measured 0.08 and 0.7 mg I lit respective. Also the avarage rate of chlorophyll a in these two areas measured 58,38 and 40.45 j.un /ht respectivly. Depending on results of correlation cofficient in "Abkenar" region we had Cyanobacters , water and air temperature , Chlorophyll a and total amount of Phosphat as a poitive correlation with transparency while Amonium and Nitrat showed , a negative correlation , EC and finally dissolved oxygen showed a very low rate of correlation coffiocient. To perform this research 5 genus of Cyanobacteres horn "Anzali" lagoon have been isolated and cultured in a laboratorial conditions Later by using Mouse Bioassay method one of these genus identified as a toxic algae. Levels of LD50 with intra peritoneal injection of toxin on mouse in 24 hours was 660 mg/kg and Levels of LC50 by using Bioassay method on Artemia and Daphnia has been shown 618 and 1000 mg kg respectively. Also the physiological effects of were investigated. algae on two types of Cypronides family called Cyprinus carpi° and Hypophrthabnichthys Resultes of blood analyses of Cypronides who were feeded by toxic algae showed a significant decline (P < 0.05) in white and red blood cells and their hematocrites. Levels of LDH , SGOT and SGPT in their blood serum had a significant increase in porportion to control group (P < 0.05) but there was no evidance a differences in Total Protein levels. Pathological studies show damage and destruction of hepato pancreas and kidney of these fishes. Signs and symptoms of intoxication caused by Cyanobacter called Planktohrix agardlltii in mouse and fish show heptotoxic character. This toxin belongs to cyclicpeptides of microcystines group.

The survey on biodiversity of phytoplankton in Iranian part of the Persian Gulf

Plankton survey of Persian Gulf was conducted Hormozgan, Bushehr and Khoozestan provinces during 4 seasons in 1998. In generally 244 species were Identified in Iranian area of Persian Gulf that consisted of 124 species of Bacillarophyceae, 114 species of Dinophyceae, 5 species of Cyanophyceae, species of Chrysophyceae and 1 species of Euglenophyceae Result shows that the density and diversity of phytoplankton compare to last years (1976-1977) changed dramaticaly. the density of phytoplankton increased from east to west of Gulf and during the year were observed two major pike in late summer and late winter. Density and diversity of phytoplankton in Koozestan region were more than other rigion. Seasonal average of phytoplankton in Hormozgan, Bushehr and Khoozestan were 1413622, 1440411 and 2237437 number/m3 respectively. Zooplankton had related inversly to phytoplankton where with increasing Zooplankton, decrease in phytoplankton were observed. Phytoplanktonic density and diversity decreas profundly changed slightly during years ago where the blue green algae had prevalent presence at all regions and the diatoms density decreased. Density of phytoplankton increased from surface to depth zom but decreased under it, however at winter incraese of phytoplankton were observed to depth 50 meter. Statistical test shows that density of phytooplankton in different depths and regions has not significantly differences, also the seasonaly denity of phytoplankton had seasonaly significantly differences too. Tuky test and clustering analysis shows that Shanon wiener diversity index at Khoozastan an Bushehr are siginificantly diffrences.

The status and significance of invertebrate communities

Invertebrates constitute a major link in energy flow culminating into fish production in aquatic ecosystems. In tropical water bodies relatively little research has been done on invertebrate ecology especially their role in fishery production. European scientists through periodic expeditions to Africa in the last quarter of the 20th century carried out the earliest research on zooplankton. Rzoska (1957) listed these early workers including Stuhlmann (1888), Weltner (1897) and Mrazek (1897-1898). Daday (1907), Verestchagin (1915) and Delachaux (1917) undertook further work during the early twentieth century. These earlyworks provide a useful basis for tracking community changes by comparison with modem investigations. Worthington (1931) provided the first quantitative account of the zooplankton of Lake Victoria along with information on diurnal vertical migrations, compared to a temperate lake. The establishment of the East African Freshwater Fisheries Research Organisation (EAFFRO) at Jinja in 1947 enabled investigations on the fisheries, algae, invertebrates and water quality aspects of the lake (EAFFRO Annual Reports 1947-1977) to be regularly carried out. Macdonald (1956) made the first detailed observations on the biology of chaoborids and chironomids (IakefJies) in relation to the feeding of the elephant snout fish, Mormyrus kannume. A detailed study of the biology of the mayfly, Povilla adusta Navas with special reference to the diurnal rhythms of activity was carried out by Hartland-Rowe (1957). The search to unravel the ecological role of aquatic invertebrates in the production dynamics of the lake has taken invertebrate research to greater heights through recent investigations including Okedi (1990), Mavut

Potential risks of contaminants with specific reference to mercury

Fresh water and fish are important to the people who live in the Lake Victoria region therefore the quality of the water and fish is of major importance (Johnson & Odada, 1996). It is well known that dirty water and spoilt fish can lead to poor health and lower standards of living, and that quality can be affected by the pollution in the environment. Even though Lake Victoria is very large, it is relatively shallow and the water remains in the lake basin for a long time (Bootsma & Hecky, 1993). There are a number of environmental issues in Lake Victoria, including water hyacinth~over-population and increased farming causing problems with the lake ecosystem. All these factors combine to keep contaminants within the lake for long time, which will lead to gradually increasing concentrations in the lake. Pollution is a term that covers a wide variety of chemicals and physical changes and their adverse effects on the environment. Here we focus on contaminants, which are unwanted chemicals introduced to the environment. Contaminants include a very wide variety of chemicals, both man-made and natural, for example, mercury, pesticides and herbicides, heavy metals, and natural plant and algae toxins. Many contaminants do not always lead to adverse effects immediately, but can gradually induce long-term problems leading to chronic illnesses and physical damage. A few contaminants have very rapid impacts resulting in immediately obvious changes such as death or injury. Sources of contaminants are varied. Contaminants can get in the lake by the way of agricultural treatment of crops near the lake, industrial effluent, intentional introduction such as fish poisoning byfishermen, natural sources such as heavy metals from particular types of rocks, and even some plants naturally release their toxins. Contaminant sources are not always found near Lake Victoria.

Effects of cage fish culture on water quality and selected biological communities in northern Lake Victoria, Uganda

Growing of fish in cages is currently practiced in Uganda and was first introduced in northern Lake Victoria in 2010. An environment monitoring study was undertaken at Source of the Nile, a private cage fish farm, in Napoleon gulf, northern Lake Victoria. In-situ measurements of key environmental (temperature, dissolved oxygen, pH and conductivity) and biological (algae, zooplankton, macro-benthos) variables were made at three transects: Transect 1- the site with fish cages (WC); transect 2- upstream of the fish cages (USC-control) and Transect 3- downstream of the cages (DSC). Upstream and Downstream sites were located approximately 1.0 km from the fish cages. Environment parameters varied spatially and temporally but were generally within safe ranges for freshwater habitats. Higher concentrations of SRP (0.015-0.112 Mg/L) occurred at USC during February, September and at DSC in November; NO2-N (0.217- 0.042 mg/L) at USC and DSC in February and November; NH4-N (0.0054- 0.065 Mg/L) at WC and DSC in February, May and November. Algal bio-volumes were significantly higher at WC (F (2,780)=4.619; P=0.010). Zooplankton species numbers were consistently lower at WC with a significant difference compared to the control site (P=0.032). Macro-benthos abundance was consistently higher at the site with cages where mollusks and low-oxygen and pollution-tolerant chironomids were the dominant group. Higher algal biomass, concentration of low-oxygen/pollution-tolerant macro-benthos and depressed zooplankton diversity at WC suggested impacts from the fish cages on aquatic biota.